Only got 1500km on my the GX cassette before it started slipping under load

[Stevers]

9 hours ago, Christie said:

You take good care of yoir drive train, better than most, imo.

The casette is most likely to be your problem.

If it is only slipping in one gear, that sprocket may be from a faulty batch. My guess is that the factory in the East got the heat treatment (hardening) wrong.

This would be easy to test for - find a machine shop with a tool that can measure hardness. (Any repeatable measurement will do). All the sprockets should have similar hardness, except If the problem sprocket has lower hardness, it is a factory fault.

Hardness and strength are related for steel, as a general rule increased hardness means increased strength.

If you have data, you can try to convince the local agents to exchange it, 

 

[Stevers]

9 hours ago, Christie said:

You take good care of yoir drive train, better than most, imo.

The casette is most likely to be your problem.

If it is only slipping in one gear, that sprocket may be from a faulty batch. My guess is that the factory in the East got the heat treatment (hardening) wrong.

This would be easy to test for - find a machine shop with a tool that can measure hardness. (Any repeatable measurement will do). All the sprockets should have similar hardness, except If the problem sprocket has lower hardness, it is a factory fault.

Hardness and strength are related for steel, as a general rule increased hardness means increased strength.

If you have data, you can try to convince the local agents to exchange it, 

Oh I didn’t know that was a really possible, but yeah that’s actually what I feel is going on. 

[LazyTrailRider]

On 7/27/2025 at 7:09 AM, Michael S said:

Is this the same as with your previous setup where you got more milage?  

With a bigger chairing you'll sit higher up the cassette more often with the larger cogs spreading the load over more teeth than the smaller ones. Less effective load, less wear.

I’ve just changed to Transmission from Eagle and I’m going to change from 32T to 34T to spread the load more on my expensive new T—Type cassette. 

The GX that has just come off has around 1400km on it and still in very good nick (700km on a GX chain, 700km until now on a XX1, which is still perfect), but it’s very obvious that the larger 40% of the cassette saw very little use, which is not ideal.

[117]

On 7/27/2025 at 7:09 AM, Michael S said:

With a bigger chairing you'll sit higher up the cassette more often with the larger cogs spreading the load over more teeth than the smaller ones. Less effective load, less wear.

This 👆

Good luck with trying to convince local agents to replace a cassette based on a factory fault of possible steel hardness. 

If you run a AXS system, the app allows you to see your time spent in each gear - this will give you the results to the problem, which I think Michael S has the correct solution. 

Shimano cassettes have the same problem for the lower 2 sprockets (although you can buy replacement parts) for the lower 2 sprockets. Up the chain ring and the problem goes away

[Mamil]

22 minutes ago, 117 said:

This 👆

Good luck with trying to convince local agents to replace a cassette based on a factory fault of possible steel hardness. 

If you run a AXS system, the app allows you to see your time spent in each gear - this will give you the results to the problem, which I think Michael S has the correct solution. 

Shimano cassettes have the same problem for the lower 2 sprockets (although you can buy replacement parts) for the lower 2 sprockets. Up the chain ring and the problem goes away

But what about granny?

[117]

38 minutes ago, Mamil said:

But what about granny?

What about granny? 

 

[Willie]

...

 

Edited July 28, 2025 by Willie

[DieselnDust]

A few thoughts:

1. Its worth checking the serial number with Cape Cycle Systems as they keep good records of bad batches of GX cassettes. Rear but there has been  a few.
2. Have you checked to ensure it's not your freehub that is slipping under the load in that gear? Smaller sprockets require you to apply more force to get going
3. Have you checked the cassette for a bent tooth. If there is a bent tooth its easy to remedy but CCS will warranty the cassette if it's this fault

How many km's on the current GX cassette?

[Stevers]

17 hours ago, 117 said:

This 👆

Good luck with trying to convince local agents to replace a cassette based on a factory fault of possible steel hardness. 

If you run a AXS system, the app allows you to see your time spent in each gear - this will give you the results to the problem, which I think Michael S has the correct solution. 

Shimano cassettes have the same problem for the lower 2 sprockets (although you can buy replacement parts) for the lower 2 sprockets. Up the chain ring and the problem goes away

Thanks yeah I like that idea too and have ordered a 34 tooth chainring. Im using a mechanical derailleur. 

[U1Nanimous]

7 hours ago, Stevers said:

Thanks yeah I like that idea too and have ordered a 34 tooth chainring. Im using a mechanical derailleur. 

If you don't mind, take a pick of the Cassette and chain, with the link please, and post here. Had a similar issue while back... 

[Stevers]

3 hours ago, U1Nanimous said:

If you don't mind, take a pick of the Cassette and chain, with the link please, and post here. Had a similar issue while back... 

[Stevers]

On 7/28/2025 at 10:30 PM, DieselnDust said:

A few thoughts:

1. Its worth checking the serial number with Cape Cycle Systems as they keep good records of bad batches of GX cassettes. Rear but there has been  a few.
2. Have you checked to ensure it's not your freehub that is slipping under the load in that gear? Smaller sprockets require you to apply more force to get going
3. Have you checked the cassette for a bent tooth. If there is a bent tooth its easy to remedy but CCS will warranty the cassette if it's this fault

How many km's on the current GX cassette?

Thanks. I hadn't considered the free hub slipping. It a DT350, and from what I hear they're pretty bombproof?  Oh Ill have good look over the cassette. See pictures of it below if your interested.

[DieselnDust]

1 hour ago, Stevers said:

Thanks. I hadn't considered the free hub slipping. It a DT350, and from what I hear they're pretty bombproof?  Oh Ill have good look over the cassette. See pictures of it below if your interested.

The star ratchet can slip if it hasn’t been serviced regularly. Could be grease thickening up or dirt preventing full engagement or wear on the edge of the teeth. Do you have the 18,36 or 54 tooth ratchet?

[Stevers]

On 7/28/2025 at 10:30 PM, DieselnDust said:

A few thoughts:

1. Its worth checking the serial number with Cape Cycle Systems as they keep good records of bad batches of GX cassettes. Rear but there has been  a few.
2. Have you checked to ensure it's not your freehub that is slipping under the load in that gear? Smaller sprockets require you to apply more force to get going
3. Have you checked the cassette for a bent tooth. If there is a bent tooth its easy to remedy but CCS will warranty the cassette if it's this fault

How many km's on the current GX cassette?

I had a look at the free hub.  It's very clean, and there's no evidence of it slipping. Once those 32 little star teeth are engaged its hard to imaging how they would slip.

[Stevers]

15 hours ago, DieselnDust said:

The star ratchet can slip if it hasn’t been serviced regularly. Could be grease thickening up or dirt preventing full engagement or wear on the edge of the teeth. Do you have the 18,36 or 54 tooth ratchet?

Its really clean and lubricated, 36 teeth

 

[Stevers]

 

This is the gear that the chain is slipping on. This was a brand new xx1 chain GX cassette (XG1275) and GX chainring 1339km ago.   There is obviously a lip on some of the teeth, from mushrooming I suppose.  Confused about why the cassette looks like this so early when I ve had over 11000 km from mt other 12 speed sram cassettes. (see the very first post)